Grid structures have been proposed for applications requiring exceptionally light weight and high strength, e.g., for supporting antennas and reflective surfaces in extraterrestrial space. It has further been proposed to fabricate such grid structures from fiber-reinforced matrix materials. In general, a fiber-reinforced matrix material could be formulated using fibers made of graphite, aramide, fiberglass, ceramic material, metallic material or thermoplastic material, and using a matrix made of a thermosetting resin (e.g., epoxy, polyester, phenolic, polymide) or a thermoplastic material. Graphite-epoxy composites are well-known fiber-reinforced matrix materials.
In the prior art, grid structures were typically fabricated by bonding together separate panels (called "grid sections"), which could be either planar or curved, to form structures of "eggcrate" or "honeycomb" configuration.
In a typical grid structure of eggcrate configuration in the prior art, separate grid sections appear to intersect each other so as to define interstices that are arrayed in a geometrically regular pattern resembling an eggcrate. However, the intersecting grid sections of a typical eggcrate-type grid structure of the prior art do not actually intersect each other in the sense that two abstract mathematical surfaces (planar or curved) can penetrate each other without breaching the integrity of either surface. When two grid sections of a typical eggcrate-type grid structure of the prior art "intersect" each other, it is generally necessary that at least one grid section (or a portion thereof) be cut so that the other grid section (or a portion thereof) can be positioned in the cut. The two "intersecting" grid sections are then bonded to each other by an adhesive bonding material, which is ordinarily spread along edges of the cut.
In a typical grid structure of honeycomb configuration in the prior art, separate grid sections are corrugated so as to have flat surface portions that are usually equally spaced with respect to each other. The flat surface portions of each grid section are positioned in contact with corresponding flat surface portions of adjacent grid sections, and the contacting surface portions of the adjacent grid sections are adhesively bonded together to define interstices between the adjacent grid sections. The resulting interstices are arrayed in a geometrically regular pattern resembling a honeycomb.
In a conventional eggcrate-type or honeycomb-type of grid structure, the strength of the grid structure necessarily depends upon the strength of the adhesive bonds by which the intersecting or contacting grid sections are secured to each other. In general, a grid structure of the eggcrate type is most prone to failure at the places where cuts have been made in intersecting grid sections, and a grid structure of the honeycomb type is most prone to failure at the places where contacting surface portions of adjacent grid sections are bonded together.
In a conventional eggcrate-type or honeycomb-type of grid structure, the weight of the adhesive bonding material that is applied where separate grid sections intersect or make contact with each other generally introduces a nonuniformity in weight distribution throughout the grid structure. Furthermore, inhomogeneities occurring in the adhesive bonding material can cause structural weaknesses in the grid structure.